meet It. Now, since neither the wind nor the machine
for even an instant maintains exactly the same direction
and velocity, it is evident that the man who would trace
the course of the centre of pressure must be very quick
of mind ; and he who would attempt to move his body
to that spot at every change must be very active indeed.
Yet this is what Herr Lilienthal attempted to do, and did
do with most remarkable skill, as his 2,000 glides suffi-
ciently attest. However, he did not escape being
overturned by wind gusts several times, and finally lost
his life through a breakage of his machine due to
defective construction. The Pilcher machine was similar
to that of Lilienthal, and, like it, seems to have been
structurally weak, for on one occasion, while exhibiting
the flight of his machine to several members of the
Aeronautical Society of Great Britain, it suddenly
collapsed and fell to the ground, causing injuries to the
operator which proved sadly fatal. The method of
^management of this machine differed in no important
respect from that of Lilienthal, the operator shifting his
ibody to make the centres of pressure and gravity coincide.
Although the fatalities which befell the designers of these
•machines were due to the lack of structural strength
rather than to lack of control, nevertheless it had become
clear to the students of the problem that a more perfect
method of control must be evolved.
Early Gliders Compared.
The Chanute machines marked a great advance in
both respects. In the multiple-wing machine the tips
folded slightly backward under the pressure of wind
gusts, so that the travel of the centre of pressure was
thus largely counterbalanced. The guiding of the
machine was done by a slight movement of the operator's
'body toward the direction in which it was desired the
machine should go. The double-deck machine, built
and tried at the same time, marked a very great structural
advance, as it was the first in which the principles of the
•modern truss bridges were fully applied to flying machine
construction. This machine, in addition to its greatly-
improved construction and general design of parts, also
differed from the machine of Lilienthal in the operation
•of its tail.
In the Lilienthal machine the tail( instead of being
fixed in one position, was prevented by a stop from
folding downward beyond a certain point, but was free to
fold upward without any hindrance. In the Chanute
machine the tail was at first rigid, but afterwards, at the
suggestion of Mr. Herring, it was held in place by a
spring that allowed it to move slightly either upward or
downward with reference to its normal position, thus
modifying the action of the wind gusts upon it very much
to its advantage. The guiding of the machine was
effected by slight movements of the operator's body, as
in the multiple-wing machines. Both these machines
were much more manageable than the Lilienthal type,
and their structural strength, notwithstanding their
extreme lightness, was such that no fatalities, or even
accidents, marked the glides made with them, although
winds were successfully encountered much greater in
violence than any which previous experimenters had dared
to attempt.
Why I took up Flight.
My own active interest in aeronautical problems dates
back to the death of Lilienthal in 1896. The brief notice
of his death which appeared in the telegraphic news at
that time aroused a passive interest which had existed
from my childhood, and led me to take down from
the shelves of our home library a book on "Animal
OCTOBER 2, 1909.
Mechanism," by Prof. Marey, which I had already read
several times. From this I was led to read more modern
works, and as my brother soon became equally interested
with myself, we soon passed from the reading to the
thinking, and finally to the working stage.
It seemed to us that the main reason why the problem
had remained so long unsolved was that no one had been
able to obtain any adequate practice. We figured that
Lilienthar in five years of time had spent only about five
hours in actual gliding through the air. The wonder was
not that he had done so little, but that he had accom-
plished so much. It would not be considered at all safe
for a bicycle rider to attempt to ride through a crowded
city street after only five hours' practice, spread out in
bits of ten seconds each over a period of five years;
yet Lilienthal with this brief practice was remarkably
successful in meeting the fluctuations and eddies of
wind gusts.
The Glider Kite.
We thought that if some method could be found by
which it would be possible to practise by the hour instead
of by the second, there would be hope of advancing the
solution of a very difficult problem. It seemed feasible
to do this by building a machine which would be sus-
tained at a speed of 18 m.p.h.,and then finding a locality
where winds of this velocity were common. With these
conditions, a rope attached to the machine to keep it
from floating backward would answer very nearly the
same purpose as a propeller driven by a motor, and it
would be possible to practice by the hour, and without
any serious danger, as it would not be necessary to rise
far from the ground, and the machine would not have
any forward motion at all.
We found, according to the accepted tables of air
pressures on curved surfaces, that a machine spreading
200 sq. ft. of wing surface would be sufficient for our
purpose, and that places could easily be found along the
Atlantic coast where winds of 16 to 25 miles were not at
A low glide on the 1901 model. Often the machine wasonly a few inches from the ground.
all uncommon. When the winds were low, it was our
plan to glide from the tops of sandhills, and, when they
were sufficiently strong, to use a rope for our motor and
fly over one spot.
(To be continued.)
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